Phenolic foam

ABSTRACT

A phenolic foam is made by foaming and curing a formable phenolic resin composition that comprises a phenolic resin, a blowing agent, an acid catalyst and an inorganic filler. The blowing agent comprises a blend of chlorinated aliphatic hydrocarbon containing 2 to 5 carbon atoms and an aliphatic hydrocarbon containing from 3 to 6 carbon atoms mixed in a ratio of 60/40 to 95/5 parts by weight. The inorganic filler is at least one selected from a metal hydroxide, a metal oxide, a metal carbonate and metal powder. The phenolic foam has a pH of 5 or more and a water uptake less than 1 kg/m 2 . A phenolic foam with a higher pH value compared with conventional phenolic foam reduces corrosion risk when in contact with metallic materials. The phenolic foam maintains excellent long-term stable thermal insulation performance, low water uptake and fire resistance performance and by using the said blowing agent, does not harm the environment as an ozone or global warming depleting material.

Phenolic foam is used in insulation applications for constructionmaterials because of its superior thermal insulation and fire resistancecharacteristics.

It is known that the thermal conductivity of polymeric thermalinsulation materials including phenolic foam can change with time. Thisphenomenon is caused by the gradual diffusion out of gas from inside thefoam cells. The gas present inside the foam cells is the blowing agentused in the foaming process. The gas in the foam cells is slowlyreplaced by air from the atmosphere. As a result, the thermalconductivity of phenolic foam can increase with time.

It is highly desirable to achieve long-term stability for the thermalinsulation performance of phenolic foam products. It is believed thatone of the causes for the degradation of thermal insulation performanceis the reduction in the flexibility of the cell walls of phenolic foamwith time. Therefore, an object of the present invention is to impartflexibility to the cell walls and thereby maintain closed cell structurein the phenolic foam. Stable closed cell structure provides a means formaintaining stable thermal conductivity for the phenolic foam over anextended time period.

As phenolic foam contains an acid catalyst, upon exposure to water suchas rain, the acid catalyst may be extracted from the phenolic foam bysuch water. This could cause a problem when metallic materials are incontact with the phenolic foam, as metals could be susceptible tocorrosion.

Under the above-stated circumstances, the object of the presentinvention is to provide phenolic foam that has excellent thermalinsulation performance, yet also have a higher pH value when compared toconventional phenolic foam. Such a phenolic foam when in contact withmetal would have significantly reduced potential to induce metalliccorrosion.

It is a further objective to use a blowing agent that causes minimal orno harm to the environment.

STATEMENTS OF INVENTION

According to the invention there is provided a phenolic foam made byfoaming and curing a foamable phenolic resin composition that comprisesa phenolic resin, a blowing agent, an acid catalyst and an inorganicfiller characterised in that the blowing agent comprises a blend of achlorinated aliphatic hydrocarbon containing 2 to 5 carbon atoms and analiphatic hydrocarbon containing from 3 to 6 carbon atoms, in that theinorganic filler is at least one selected from a metal hydroxide and ametal carbonate, and in that the phenolic foam has a phi of 5 or more.

In one embodiment a phenolic foam as claimed in claim 1 wherein thephenolic resin has a molar ratio of phenol groups to aldehyde groups inthe range 1:1 to 1:3, preferably the molar ratio of phenol groups toaldehyde groups is from 1.5 to 23.

In one embodiment the phenolic resin has a weight average molecularweight of from 400 to 3,000, preferably from 700 to 2,000.

In one embodiment the blowing agent comprises 1 to 20 parts by weightper 100 parts by weight of phenolic resin.

In one embodiment the chlorinated aliphatic hydrocarbon is selected fromchloropropane and, its isomers. Preferably the chlorinated aliphatichydrocarbon is isopropyl chloride.

In one embodiment the blowing agent comprises isopropyl chloride and atleast one hydrocarbon selected from butane, pentane, hexane, heptane andtheir isomers. The blowing agent may comprise 60% or more but less than95% of isopropyl chloride. The blowing agent may comprise 40% or less ofthe aliphatic hydrocarbon. In one case the hydrocarbon is iso-pentaneand is present as 15% by weight of the blowing agent.

In one embodiment the blowing agent blend comprises isopropyl chlorideand iso-pentane in a weight ratio of from 60:40 to 95:05. Preferably,the blowing agent blend comprises isopropyl chloride and iso-pentane ina weight ratio of from 65:35 to 90:10. The blowing agent blend maycomprise isopropyl chloride and iso-pentane in a weight ratio of from70:30 to 85:15.

In one embodiment the acid catalyst comprises 5 to 25 parts by weightper 100 parts by weight of phenolic resin. The acid catalyst maycomprise at least one of benzenesulphonic acid, para-toluene sulphonicacid, xylene sulphonic, naphthalene sulphonic acid, ethylbenzenesulphonic acid and phenol sulphonic acid.

In one embodiment the inorganic filler is present in an amount of from 1to 20 parts by weight per 100 parts by weight of phenolic resin.

In one embodiment the filler comprises at least one of a metal oxidesuch as aluminium oxide or zinc oxide, a metal powder such as zinc, or ametal hydroxide such as aluminium hydroxide, magnesium hydroxide, or ametal carbonate such as calcium carbonate, magnesium carbonate, bariumcarbonate, zinc carbonate.

Preferably the filler may comprise at least one of a metal hydroxidesuch as aluminium hydroxide, magnesium hydroxide, or a metal carbonatesuch as calcium carbonate, magnesium carbonate, barium carbonate, zinccarbonate, preferably with a Ksp lower than 10⁻⁸ when measured at 25° C.Most preferably the filler comprises a metal carbonate such as calciumcarbonate, barium carbonate, zinc carbonate.

High quality foam has been produced using calcium-carbonate as the solefiller.

In one embodiment the foam comprises a plasticiser for the phenolicresin. The plasticiser may comprise 0.1 to 20 parts by weight per 100parts by weight of phenolic resin. The plasticiser may comprise apolyester polyol that is the reaction product of a polybasic carboxylicacid selected from a dibasic to a tetra basic carboxylic acid with apolyhydric alcohol selected from a dihydric to a pentahydric alcohol.Preferably, the polyester polyol has a number average molecular weightof 250 to 350 and a weight average molecular weight of 400 to 550.

The polybasic carboxylic acid used to synthesise the polyester polyolmay comprise at least one of phthalic acid, isophthalic acid,terephthalic acid, naphthalene-2,3-dicarboxylic acid,naphthalene-1,4-dicarboxylic acid, napththalene-2,6-dicarboxylic acid,adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid,cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid,and cyclohexane-1,4-dicarboxylic acid. Preferably the polybasiccarboxylic acid used to synthesise the polyester polyol comprises one ormore of phthalic acid, isophthalic acid, or terephthalic acid.

The polyhydric alcohol used to synthesise the polyester polyol maycomprise at least one of ethylene glycol, diethylene glycol, propyleneglycol, dipropylene glycol, 1,4-butane diol, 1,5-pentane diol,1,6-hexane diol, neopentyl glycol, 1,2-cyclohexane dimethanol,1,3-cyclohexane dimethanol, and 1,4-cyclohexane dimethanol. Preferablythe polyhydric alcohol used to synthesise the polyester polyol comprisesone or more of diethylene glycol, propylene glycol, dipropylene glycol,1,4-butane diol.

In one embodiment the phenolic foam comprises a surfactant for thephenolic resin. The surfactant may comprise 1 to 6 parts by weight per100 parts by weight of phenolic resin.

In one embodiment the surfactant is a castor oil-ethyleneoxide adductwherein more than 20 moles but less than 40 moles of ethylene oxide areadded per 1 mole of castor oil.

In one embodiment a phenolic foam comprises an organic modifier forco-reacting with the phenolic resin. The modifier may comprise 1 to 10parts by weight of a compound having an amino group per 100 parts byweight of phenolic resin. In one case at least one amino groupcontaining compound is selected from urea, dicyandiamide and melamine.Preferably, the modifier comprises approximately 5 parts by weight ofurea. per 100 parts by weight of phenolic resin

The phenolic foam has an aged thermal conductivity of 0.025 W/m.K orless when measured at a mean temperature of 10° C. after heat ageing for175±5 days at 70±2° C., in accordance with the procedure as specified inEuropean Standard EN13166:2001, Annex C, section C.4:2.3.

The phenolic foam may have a density of from 30 to 100 kg/m³, preferably10 to 45 kg/m³.

The phenolic foam may have a closed cell content of 90% or more,preferably 92.5% or more. Preferably the foam has a limiting oxygenindex of 30% or more.

Preferably, the phenolic foam has a water uptake of less than 0.9 kg/m²,most preferably a water uptake of less than 0.8 kg/m².

In one embodiment the phenolic foam has a facing on at least one surfacethereof.

The facing may comprise at least one of glass fibre-non woven fabric,spun bonded-non woven fabric, aluminium foil, bonded-non woven fabric,metal sheet, metal foil, ply wood, calcium silicate-board, plasterboard, Kraft or other paper product, and wooden board.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be more clearly understood from the followingdescription. This is given by way of example only with reference to theaccompanying FIGURE in which:

FIG. 1 shows an electron micrograph of a sample of the phenolic foamfrom Example I having a magnification of 650 times. Calcium carbonatefiller is shown dispersed among the foam cells. To prepare the foamsamples for electron microscopy analysis, foams are sputter coated witha 1.5 to 2.5 nm layer of gold in an evacuated inert atmosphere. Thisprocedure acts as an aid to see cellular defects more clearly. Electronmicroscopy can be used to demonstrate whether foam cells have defectssuch as holes or cracks.

DETAILED DESCRIPTION

The phenolic foam comprises phenolic resin, a blend of chlorinatedaliphatic hydrocarbon containing 2 to 5 carbon atoms and a low boilingpoint hydrocarbon blowing agent, an acid catalyst and an inorganicfiller to regulate foam pH. The invention provides phenolic foam with ahigher pH value than is currently typical of commercially availablephenolic foam products. The higher pH helps prevent metallic materialsfrom corroding when they are in prolonged contact with phenolic foam.

A preferred type of phenolic resin to use in the present invention is aresole resin. This resole resin can be obtained from the chemicalreaction of phenol or a phenol based compound such as cresol, xylenol,para-alkylphenol, para-phenylphenol, resorcinol, and the like with analdehyde such as formaldehyde, furfural, acetaldehyde and the like undera catalytic amount of alkali such as sodium hydroxide, potassiumhydroxide, calcium hydroxide, or an aliphatic amine like trimethylamine,or triethylamine. These types of chemical constituent are commonly usedin standard resole resin production, but the invention is not limited tojust those chemicals listed here.

The molar ratio of phenol groups to aldehyde groups is not especiallylimited. It is preferred that the molar ratio of phenol to aldehyde isin the range from 1:1 to 1:3, more preferably from 1:1.5 to 1:2.5, andparticularly preferable is 1:1.6 to 1:2.1.

A preferred weight average molecular weight suitable for the phenolicresin used in the invention is from 400 to 3,000, and more preferablyfrom 700 to 2,000. The number average molecular weight is preferablyfrom 150 to 1,000, and more, preferably from 300 to 700.

A blend of a straight chain or branched chain chlorinated aliphatichydrocarbon containing 2 to 5 carbon atoms, and a straight chain orbranched aliphatic hydrocarbon containing 3 to 6 carbon atoms is used asthe blowing agent in the present invention. The number of chlorine atomsis not especially limited but a preferred number is 1 to 4. For example,dichloroethane, propyl chloride, isopropyl chloride, butyl chloride,isobutyl chloride, pentyl chloride, isopentyl chloride and so on. Achlorinated aliphatic hydrocarbon may be selected individually or incombination with one or more other chlorinated aliphatic hydrocarbons. Achloropropane such as propyl chloride and isopropyl chloride is suitableand isopropyl chloride is more preferable.

The aliphatic hydrocarbon containing 3 to 6 carbon atoms used incombination with the chlorinated aliphatic hydrocarbon includes butane,pentane, hexane, heptane and the like. Isobutane and isopentane areparticularly preferable.

The blowing agent used in the present invention comprises thechlorinated aliphatic hydrocarbon having 2 to 5 carbon atoms and thealiphatic hydrocarbon having 3 to 6 carbon atoms. A gas such as air,nitrogen, helium, argon, and carbon dioxide, and a fluorocarbon may beadded to the foamable phenolic resin composition in such an amount thatdoes not impair characteristics or physical properties of the phenolicfoam of the present invention. A preferred amount of the substance to beadded is 0.1 to 10% by weight, and more preferred is 0.5 to 1.5% byweight of blowing agent used.

The relative weight proportions of chlorinated aliphatic hydrocarboncontaining 2 to 5 carbon atoms to the aliphatic hydrocarbon having 3 to6 carbon atoms can vary on a weight basis from 60% to 95% of chlorinatedaliphatic hydrocarbon containing 2 to 5 carbon atoms mixed with 40% to5% of low boiling point hydrocarbon respectively.

The amount of the blowing agent used in the present invention is from 1to 20 parts by weight relative to 100 parts by weight of phenolic resin,more preferably from 7 to 14 parts by weight per 100 parts by weight ofphenolic resin.

Isopropyl Chloride (2-chloropropane) can be selected for its favourableenvironmental characteristics. Isopropyl Chloride (2-chloropropane) hasbeen reported as having no global warming potential or ozone depletioncharacteristics.

(Reference is United States Environmental Protection Agency, 40 CFR Part82. FLR-6718-2 Protection of Stratospheric Ozone. Section II Listing ofAcceptable Substitutes, B Foam Blowing 1b, 2-Chloropropane.

Hydrocarbons such as iso-pentane or isobutane also have low potentialfor global warming and do not deplete the ozone layer of the Earth.

It has been found that a blend of chlorinated aliphatic hydrocarboncontaining 2 to 5 carbon atoms, such as isopropyl chloride, and lowboiling hydrocarbon can be used as a blowing agent for phenolic foam.The foams produced are essentially free of cellular defects, and givestable low thermal conductivity values. Such foams are used asinsulation products for buildings and transport.

The addition of inorganic filler to the phenolic foam of the presentinvention reduces residual acidity, and can improve fire performancewhilst still maintaining low thermal conductivity.

The amount of inorganic filler used is preferably from 0.1 to 30 partsby weight, and more preferably, from 1 to 10 parts by weight relative to100 parts by weight of phenolic resin. In one embodiment the fillercomprises at least one of a metal oxide such as aluminium oxide or zincoxide, a metal powder such as zinc, or a metal hydroxide such asaluminium hydroxide, magnesium hydroxide, or a metal carbonate such ascalcium carbonate, magnesium carbonate, barium carbonate, zinccarbonate. Preferably the filler may comprise at least one of a metalhydroxide such as aluminium hydroxide, magnesium hydroxide, or a metalcarbonate such as calcium carbonate; magnesium carbonate, bariumcarbonate, zinc carbonate, preferably with a Ksp lower than 10⁻⁸ whenmeasured at 25° C.

The use of an organic amino group containing compound, such as urea, inthe foam of the present invention, can lower thermal conductivity,increase strength and reduce friability of the phenolic foam. Apreferred amount of urea to be used in the present invention is in therange from 1 to 10 parts by weight, preferably, from 3 to 7 parts byweight relative to 100 parts by weight of the phenolic resin.

For the acid catalyst used to initiate polymerisation of the phenolicresin in the invention, individual or blends of strong organic acidssuch as benzene sulphonic acid, para toluene sulphonic acid, xylenesulphonic acid, ethylbenzene sulphonic acid, naphthalene sulphonic acid,phenol sulphonic acid and the like are used. Phenol sulphonic acid, paratoluene sulphonic acid, and xylene sulphonic acid are particularlypreferred. An inorganic acid such as sulphuric acid, phosphoric acid andthe like, may be optionally used with the said organic acids.

The amount of acid used to initiate polymerisation of the phenolic resinvaries with the type of acid selected, but is usually in a range from 5to 25 parts by weight, and more preferably from 7 to 22 parts by weightrelative to 0.100 parts by weight of phenolic resin. The most preferableamount of acid to use is from 10 to 20 parts by weight of phenolicresin.

The phenolic resin used herein contains a surfactant to aid foammanufacture. The surfactant used is a castor oil-ethylene oxide adductwherein more than 20 moles but less than 40 moles of ethylene oxide areadded per mole of castor oil. The weight addition of the castor oil-EOadduct relative to 100 parts by weight of phenolic resin is preferablyfrom 1 to 5 parts by weight, and more preferably from 2 to 4 parts byweight. If the content of the castor oil-EO adduct is less than 1 partby weight, uniform foam cells cannot be obtained. On the other hand, ifmore than 5 parts by weight of the castor oil-EO adduct is used, productcost and the water-absorption capacity of the foam is increased.

In accordance with the present invention, there is provided aplasticiser for the phenolic foam. A polyester polyol is the preferredplasticiser.

The plasticiser imparts flexibility to the cell walls of the phenolicfoam, inhibits their degradation over time, and improves long termthermal insulation stability. The plasticiser of the present inventionis a polyester polyol that is obtained from the reaction of a polybasiccarboxylic acid with a polyhydric alcohol. In terms of impartingflexibility to the cell-walls of phenolic foam, the molecular weight ofthe plasticiser is not especially limited. However, a polyester polyolhaving a weight average molecular weight from 200 to 10,000, andparticularly from 200 to 5,000, is preferred.

The polyhydric alcohol used preferably has at least two hydroxyl groupsin a molecule. The number of hydroxyl groups in a molecule of thepolyhydric alcohol used is at least more than 1.

The number of carboxyl groups in a molecule of the said polybasiccarboxylic acid is at least more than 1.

The polyester polyol of the present invention is for example, thereaction product of a polybasic carboxylic acid selected from a dibasicto a tetrabasic carboxylic acid with a polyhydric alcohol selected froma dihydric to a pentahydric alcohol. A product expressed in the Formula(I) below is preferable, wherein A is a dicarboxylic acid residueoriginally containing up to two hydrogen atoms from a dibasic carboxylicacid, and R is a chemical backbone of a dihydric alcohol originallycontaining up to two hydroxyl groups from a dihydric alcohol, and n isan integer equal to or more than 1.

In the general formula (I), a preferred dibasic carboxylic acid formingthe residue A is either an aromatic dicarboxylic acid, an aliphaticdicarboxylic acid or an alicyclic dicarboxylic acid. These carboxylicacids preferably include phthalic acid, isophthalic acid, terephthalicacid, naphthalene-2,3-dicarboxylic acid, naphthalene-1,4-dicarboxylicacid, napththalene-2,6-dicarboxylic acid, adipic acid, pimeric acid;suberic acid, azelaic acid, sebacic acid, cyclohexane-1,2-dicarboxylicacid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylicacid and the like.

The dihydric alcohol forming chemical backbone R is an aromatic glycol,an aliphatic glycol or an alicyclic glycol which preferably includesethylene glycol, diethylene glycol, propylene glycol, dipropyleneglycol, 1,4-butane diol, 1,5-pentane diol, 1,6-hexane diol, neopentylglycol, 1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, and1,4-cyclohexane dimethanol, cyclopentane-1,2-diol,cyclepentane-1,2-dimethanol, cyclohexane-1,2-diol, cyclohexane-1,3-diol,cyclohexane-1,4-diol, cyclopentane-1,4-dimethanol,2,5-norbornane dioland the like. Aliphatic glycols and alicyclic glycols are especiallypreferable.

A reaction product so obtained is a mixture in which “n” is composed ofvarious values and the hydroxyl value of these reaction products isusually included in a range of from 10 to 500 mg-KOH/g.

Since the plasticiser for the phenolic foam in the present invention hasa molecular structure containing both an ester backbone and a hydroxylgroup, it is hydrophilic as is the phenolic resin. Therefore thephenolic resin and the plasticiser are compatible and together can forma homogeneous resin solution. Furthermore, it is presumed that when thesaid polyester polyol, is added to a foamable phenolic resincomposition, the polyester polyol imparts flexibility to the cell-wallsof the phenolic foam. Therefore, even after extensive ageing,degradation phenomenon such as a crack-occurrence at the cell-walls iscontrolled. This leads to long-term stability for the thermalconductivity of the phenolic foam.

Also the combination of the plasticizer and organic filler results in animproved water uptake. Moisture is one of the thriving forces ofcorrosion. Therefore the water uptake of the product should be limitedbelow 1 kg/m².

The phenolic foam of the present invention has an aged thermalconductivity below 0.025 W/m.K (at a mean temperature of 10° C.).Phenolic foam that has an aged thermal conductivity more than 0.025W/m.K is less efficient in terms of thermal insulation performance.

The surface of the phenolic foam products of the present invention maybe covered with a facing material. Surface facing materials includenon-woven fabrics made of natural fibre, synthetic fibre or inorganicfibre. Paper or Kraft paper, aluminium foil and so on can be used asfacing material.

A process for producing phenolic foam of the invention with a pH above5.0 is described that uses a phenolic resin composition that containsphenolic resin, an acid catalyst, a blend of chlorinated aliphatichydrocarbon containing 2 to 5 carbon atoms and an aliphatic hydrocarbonas blowing agent, and an inorganic filler to raise the pH of the foam.The phenolic resin used could also contain plasticiser, surfactant, anda chemical compound having amino groups. The said blowing agent mixture,and acid catalyst are generally added to the phenolic resin compositionin a foam mixing head at the time of foam manufacture.

As stated, to the resin composition used in producing phenolic foam ofthe present invention, is added an amino group containing compound. Thisis preferably urea powder that is mixed into the phenolic resin at 18°C. to 22° C. for 1 to 5 hours prior to making foam. Alternatively anamino group containing compound like urea can be reacted withformaldehyde in the presence of phenol during the manufacture of thephenolic resin.

Castor oil-EO adduct surfactant, an inorganic filler such as calciumcarbonate powder with mean particle size 50 to 200 μm, and preferably, apolyester polyol plasticiser are also mixed into the phenolic resin.

The phenolic resin composition obtained is pumped to a high speed mixerhead where it is introduced to and mixed in with the blend ofchlorinated aliphatic hydrocarbon containing 2 to 5 carbon atoms and lowboiling point hydrocarbon blowing agent and an acid catalyst to preparea foamable phenolic composition.

According to the process for producing phenolic foam of the presentinvention, the said foamable phenolic resin composition is discharged onto a continuous running facing material carrier and passed through aheated zone for foaming and moulding into phenolic foam products ofpredetermined shape. In this manufacturing process, the said resincomposition that has been discharged on to a running facing materialcarrier on a conveyor belt passes into a heated oven typically at 50 to100° C. for approximately 2 to 15 minutes. The top surface of the risingfoam composition is pressed down with another facing material carried onan upper conveyer belt. The thickness of the foam is controlled to therequired predetermined thickness. The phenolic foam leaving the oven isthen cut to a predetermined length.

The use of an appropriate blend of isopropyl chloride and iso-pentane asthe blowing agent for example, is environmentally friendly but stillallows closed cell phenolic foam to be produced, thereby maintainingthermal insulation performance. The phenolic foam in the presentinvention comprises foaming and curing a foamable phenolic resincomposition comprising a phenolic resin, an acid catalyst, a blend ofchlorinated aliphatic hydrocarbon containing 2 to 5 carbon atoms and lowboiling point aliphatic hydrocarbon as blowing agent, and an inorganicfiller.

In accordance with the present invention, corrosion-resistant phenolicfoam is provided by using a blend of chlorinated aliphatic hydrocarboncontaining 2 to 5 carbon atoms and aliphatic hydrocarbon blowing agent,and additionally controlling the amount of acid catalyst and adding aninorganic filler such as calcium carbonate to the foam. The phenolicfoam produced has excellent fire resistance performance, long-termthermal insulation performance stability, low water uptake and a higherpH value than is normally obtained with phenolic foam products. Furtherthe blowing agent used has favourable properties regarding globalwarming potential and ozone depletion.

The invention described herein overcomes the potential corrosion risk tometal in contact with phenolic foam by providing a means of partiallyneutralising the residual acid in the phenolic foam using an inorganicfiller.

The higher pH foam, can prevent metal in contact with the phenolic foamfrom becoming corroded. The higher pH foam can prevent metal in contactwith the phenolic foam from becoming corroded. The phenolic foam of thepresent invention has a pH of 5.0 or more. If the pH is 5.0 or more, thecorrosion of metal can be inhibited when in contact with or adjacent tothe said phenolic foam even when the metal is wet. A preferable pH forthe phenolic foam of the invention is 5.5 or more and especiallypreferable is when pH is 6.0 or more. The method for the determinationof pH is described later.

The phenolic foam of the present invention has an aged thermalconductivity of below 0.025 W/m.K. The thermal insulation performance ofphenolic foam with an aged thermal conductivity above 0.025 W/m.K isundesirable regarding insulation performance.

The phenolic foam in the present invention has typically a density of 10to 45 kg/m³, and an average cell diameter of 5 to 400 μm.

The phenolic foam of the present invention has substantially no holes inthe cell-walls.

The phenolic foam of the present invention has a closed cell content of90% or more, preferably 92.5% or more.

The phenolic foam in the present invention has preferably an oxygenindex of 30 or more.

The long-term stability of the phenolic foam cells is maintained becausethe phenolic foam cells of the present invention have improvedflexibility.

Suitable testing methods for measuring the physical properties ofphenolic foam are described below.

(1) Foam Density

This was measured according to EN 1602: Thermal insulating products forbuilding applications Determination of the apparent density

(2) Thermal Conductivity

A foam test piece of length 300 mm and width 300 mm was placed between ahigh temperature plate at 20° C. and a low temperature plate at 0° C. ina thermal conductivity test instrument (LaserComp Type FOX314/ASF,Inventech Benelux BV). The thermal conductivity of the test pieces wasmeasured according to EN 12667: Thermal performance of buildingmaterials and products—Determination of thermal resistance by means ofguarded hot plate and heat flow meter methods, Products of high andmedium thermal resistance.

(3) Thermal Conductivity after Accelerated Ageing

This was measured using EN 13166: Thermal insulation products forbuildings—Factory made products of phenolic foam-Specification Annex Csection 4.2.3. The thermal conductivity is measured after exposing foamsamples for 25 weeks at 70° C. and stabilisation to constant weight at23° C. and 50% R.H. This thermal ageing serves to provide an estimatedthermal conductivity for a time period of 25 years at ambienttemperature.

(4) pH

0.5 g of phenolic foam is pulverised to pass through a 250 μm (60 mesh)sieve and is then put into a 200 ml-Erlenmeyer flask. 200 ml ofdistilled water are added and the contents are sealed with a stopper.After stirring at 23±5 for 7 days with a magnetic follower, the contentsof the flask are tested for pH.

(5) Average Cell Diameter

A flat section of foam is obtained by slicing through the middle sectionof the thickness of the foam board in a direction running parallel tothe top and bottom faces of a foam board. A 50-fold enlarged photocopyis taken of the cut cross section of the foam. Four straight lines oflength 9 cm are drawn on to the photocopy. The number of cells presenton every line is counted and the average number cell number determinedaccording to TIS K6402 test method. The average cell diameter is takenas 1800 μm divided by this average number.

(6) Voids

A flat section of foam is obtained by slicing through the middle sectionof the thickness of the foam board in a direction running parallel tothe top and bottom faces. A 200-fold enlarged photocopy is taken of thiscut cross section of foam covering an area 100 mm by 150 mm. Atransparent graph paper is placed on top of the photocopy of the cutfoam section. The area of voids that occupy 8 or more 1 mm by 1 mmsquares of graph paper was added up to calculate the voids area ratio.Eight squares is equivalent to 2 mm² area of actual foam.

(7) Oxygen Index

The oxygen index at room temperature of phenol foam was determinedaccording to JIS K7201-2 test method.

(8) Closed Cell Ratio

The closed cell ratio was determined according to ASTM D2856 testmethod.

(9) Water Uptake

The water uptake was determined according to EN1609:1996 ThermalInsulating products for building applications—Determination of shortterm water absorption by partial immersion.

(10) Friability

Friability is measured according test method ASTM C 421-88.

The present invention is explained in detail by the Examples andComparative Example that follow. The physical properties of the phenolicfoams obtained are shown in Table 1 below. However, the invention is notlimited only to these Examples and Comparative Example.

EXAMPLES

The phenolic resins used in the invention are phenolic resole Resins Aand B and are described as follows.

Phenolic resole Resin A is a commercially available liquid PhenolFormaldehyde resin supplied by Sumitomo Bakelite under the trade nameR300. This resin has a viscosity of 8000-10000 centipoise (cP) at 25°C., weight average molecular weight 800 to 1200 and pH 5.3 to 6.3.

R330 resin contains from 2% to 4% free phenol and 3% to 4% freeformaldehyde. R330 resin has a Phenol: Formaldehyde molar ratio of 1:2and a water content of 11-13% (measured by Karl Fisher analysis). Tothis resin, between 2 and 5% surfactant as described previously herein,is added.

Phenolic resole Resin B is a liquid Phenol-Urea-Formaldehyde resin. Thisresin has a viscosity of 13000-18000 cp at 25° C., weight averagemolecular weight 500 to 700, and pH 5.3 to 6.3.

Resin B resin contains from 2% to 4% free phenol and 1% to 2% freeformaldehyde.

Resin B has a Phenol: Urea: Formaldehyde molar ratio of 1:0.25:2.0 and awater content of 11-13% (measured by Karl Fisher analysis). To thisresin between 2 and 5% surfactant as described previously herein, isadded.

The following Examples 1 and 5 show how foam samples of the inventionare made.

Example 1

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 6.1 g of a plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of calciumcarbonate powder (Durcal 130 supplied by Omya) of average particle size170 μm is added and mixed into the resin until it is uniformlydispersed. Next, 21.0 g of pre-blended isopropyl chloride/iso-pentane(85/15 parts by weight) as blowing agent at 1° C. is mixed into theresin. Once a uniform emulsion has formed, the resin mixture is cooledto between 5° C. and 10° C. Next, 40 g of liquid para-toluene sulphonicacid/xylene sulphonic acid blend (65/35 parts by weight) at 92%concentration, at 8° C. is quickly mixed in. Foaming commencesimmediately. Mixing of the acid into resin takes less than 10 secondsand 200 g of the resin mix is quickly poured into a 30×30×5.0 cm pictureframe mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

FIG. 1 shows an electron micrograph of a sample of the phenolic foamfrom Example 1 with a magnification of 650 times. Calcium carbonatefiller is shown dispersed among the foam cells.

Example 2

Here the ratio of isopropyl chloride to iso-pentane is adjusted to 70/30parts per weight)

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 6.1 g of plasticizer as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 122 g of calciumcarbonate powder (Durcal 130 supplied by Omya) is added and mixed intothe resin until it is uniformly dispersed. Next, 21.0 g of pre-blendedisopropyl chloride/iso-pentane (70/30 parts by weight) as blowing agentat 1° C. is mixed into the resin. Once a uniform emulsion has formed,the resin mixture is cooled to between 5° C. and 10° C. Next, 40 g ofliquid para-toluene sulphonic acid/xylene sulphonic acid blend (65/35parts by weight) at 92% concentration, at 8° C. is quickly mixed in.Foaming commences immediately. Mixing of the acid into resin takes lessthan 10 seconds and 200 g of the resin mix is quickly poured into a30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Example 3

Here there is a higher addition of plasticiser to the resin (12.2 ginstead of 6.1 g).

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 12.2 g of plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of calciumcarbonate powder (Durcal 130 supplied by Omya) is added and mixed intothe resin until it is uniformly dispersed. Next, 21.0 g of pre-blendedisopropyl chloride/iso-pentane (85/15 parts by weight) as blowing agentat 1° C. is mixed into the resin. Once a uniform emulsion has formed,the resin mixture is Cooled to between 5° C. and 10° C. Next, 40 g ofliquid para-toluene sulphonic acid/xylene sulphonic acid blend (65/35parts by weight) at 92% concentration, at 8° C. is quickly mixed in.Foaming commences immediately. Mixing of the acid into resin takes lessthan 10 seconds and 200 g of the resin mix is quickly poured into a30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Example 4

Here there is the addition of a lower amount of urea to the resin (6.1 ginstead of 12.2 g).

To 244 g of Resin A, at 11-15° C., is mixed with 6.1 g of powdered ureaand 6.1 g of plasticizer as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of calciumcarbonate powder (Durcal 130 supplied by Omya) is added and mixed intothe resin until it is uniformly dispersed. Next, 21.0 g of pre-blendedisopropyl chloride/iso-pentane (85/15 parts by weight) as blowing agentat 1° C. is mixed into the resin. Once a uniform emulsion has formed,the resin mixture is cooled to between 5° C. and 10° C. Next, 40 g ofliquid para-toluene sulphonic acid/xylene sulphonic acid blend (65/35parts by weight) at 92% concentration, at 8° C. is quickly mixed in.Foaming commences immediately. Mixing of the acid into resin takes lessthan 10 seconds and 200 g of the resin mix is quickly poured into a30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Example 5

To 244 g of Resin B, at 11-15° C., is mixed with 6.1 g of plasticiser asdescribed previously herein and 12.2 g of calcium carbonate powder(Durcal 130 supplied by Omya) which is mixed until uniformly dispersed.Next, 21 g of pre-blended isopropyl chloride/iso-pentane blend (85/15parts by weight) as blowing agent at 1° C. is mixed into the resin. Oncea uniform emulsion has formed, the resin mixture is cooled to between 5°C. and 10° C. Next, 40 g of liquid para-toluene sulphonic acid/xylenesulphonic acid blend (65/35 parts by weight) at 92% concentration, at 8°C. is quickly mixed in. Foaming commences immediately. Mixing of theacid into resin takes less than 10 seconds and the resin mix is quicklypoured into a 30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Comparative Example 1

The following comparative example describes the manufacture of a foamwithout calcium carbonate filler.

To 244 g of Resin A, at 11-15° C., is mixed 12.2 g with powdered ureaand 6.1 g of plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Next, 21 g of pre-blendedisopropyl chloride/iso-pentane (85/15 parts by weight) as blowing agentat 1° C. is mixed into the resin. Once a uniform emulsion has formed,the resin mixture is cooled to between 5° C. and 10° C. Next, 40 g ofliquid para-toluene sulphonic acid/xylene sulphonic acid blend (65/35parts by weight) at 92% concentration, at 8° C. is quickly mixed in.Foaming commences immediately. Mixing of the acid into resin takes lessthan 10 seconds and the resin mix is quickly poured into a 30×30×5.0 cmpicture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m3.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Comparative Example 1 demonstrates that a good quality phenolicinsulation foam can be produced without the filler present, but theresulting foam shows a pH<5.0 and a water uptake >1.0 kg/m² when testedto test methods (4) and (5) as given above (see Table 1 for resultssummary).

Comparative Example 2

The following comparative example describes the manufacture of a foamwith magnesium carbonate as filler.

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 6.1 g of plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of magnesiumcarbonate powder (supplied by Sigma-Aldrich product code M-7179) isadded and mixed into the resin until it is uniformly dispersed. Next, 21g of pre-blended isopropyl chloride/iso-pentane (85/15 parts by weight)as blowing agent at 1° C. is mixed into the resin. Once a uniformemulsion has formed, the resin mixture is cooled to between 5° C. and10° C. Next, 40 g of liquid para-toluene sulphonic acid/xylene sulphonicacid blend (65/35 parts by weight) at 92% concentration, at 8° C. isquickly mixed in. Foaming commences immediately. Mixing of the acid intoresin takes less than 10 seconds and the resin mix is quickly pouredinto a 30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Comparative Example 2 demonstrates that use of a filler with a highsolubility parameter (Ksp>1×10⁻⁸) can produce a foam, but the resultingfoam shows a water uptake >1.0 kg/m² when tested to test method (9), andpoorer foam structure caused by reaction of the filler with the acidcatalyst which results in higher thermal conductivity (see Table 1).

Comparative Example 3

The following comparative example describes the manufacture of a foamwith isopropyl chloride only as a blowing agent.

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 6.1 g of plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of calciumcarbonate powder (Durcal 130 supplied by Omya) is added and mixed intothe resin until it is uniformly dispersed. Next, 21.0 g of isopropylchloride as blowing agent at 1° C. is mixed into the resin. Once auniform emulsion has formed, the resin mixture is cooled to between 5°C. and 10° C. Next, 40 g of liquid para-toluene sulphonic acid/xylenesulphonic acid blend (65/35 parts by weight) at 92% concentration, at 8°C. is quickly mixed in. Foaming commences immediately. Mixing of theacid into resin takes less than 10 seconds and 200 g of the resin mix isquickly poured into a 30×30×5.0 cm picture frame mould preheated to70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Comparative Example 3 demonstrates that use of 100% isopropyl chlorideas blowing agent gives a poorer foam structure which results in higheraged thermal conductivity performance (see Table 1), and larger cellswith a high aspect ratio (typically >3:1). The high aspect ratio isundesirable for practical use of the foam as poor compressive strengthis seen across the narrow cell dimension, which will result in shrinkageof the foam in situ.

Comparative Example 4

The following comparative example describes the manufacture of a foamwith a ratio of isopropyl chloride to iso-pentane of 50/50 parts byweight.

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 6.1 g of plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of calciumcarbonate powder (Durcal 130 supplied by Omya) is added and mixed intothe resin until it is uniformly dispersed. Next, 21.0 g of pre-blendedisopropyl chloride/iso-pentane (50/50 parts by weight) as blowing agentat 1° C. is mixed into the resin. Once a uniform emulsion has formed,the resin mixture is cooled to between 5° C. and 10° C. Next, 40 g ofliquid para-toluene sulphonic acid/xylene sulphonic acid blend (65/35parts by weight) at 92% concentration, at 8° C. is quickly mixed in.Foaming commences immediately. Mixing of the acid into resin takes lessthan 10 seconds and 200 g of the resin mix is quickly poured into a30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had a apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Comparative Example 4 demonstrates that use of <60% isopropyl chlorideand >40% iso-pentane as blowing agent gives an inferior foam structurewhich results in higher aged thermal conductivity values (see Table 1),caused by poorer integrity of the cell wall structure.

Comparative Example 5

The following comparative example describes the manufacture of a foamwithout the addition of a plasticiser.

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powderedurea. The resin is allowed to stand for between 2 and 24 hours. Then,12.2 g of calcium carbonate powder (Durcal 130 supplied by Omya) isadded and mixed into the resin until it is uniformly dispersed. Next,21.0 g of pre-blended isopropyl chloride/iso-pentane (85/15 parts byweight) as blowing agent at 1° C. is mixed into the resin. Once auniform emulsion has formed, the resin mixture is cooled to between 5°C. and 10° C. Next, 40 g of liquid para-toluene sulphonic acid/xylenesulphonic acid blend (65/35 parts by weight) at 92% concentration, at 8°C. is quickly mixed in. Foaming commences immediately. Mixing of theacid into resin takes less than 10 seconds and 200 g of the resin mix isquickly poured into a 30×30×5.0 cm picture frame mould preheated to70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had a apparent density ofapproximately 40.5 kg/m³.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

Comparative Example 5 demonstrates that the absence of plasticiserresults in a foam with poorer cell structure which results in higheraged thermal conductivity values (see Table 1).

Comparative Example 6

The following comparative example describes the manufacture of a foamwithout the addition of urea.

To 244 g of Resin A, at 11-15° C., is mixed with 12.2 g of powdered ureaand 6.1 g of plasticiser as described previously herein. The resin isallowed to stand for between 2 and 24 hours. Then, 12.2 g of calciumcarbonate powder (Durcal 130 supplied by Omya) is added and mixed intothe resin until it is uniformly dispersed. Next, 21.0 g of pre-blendedisopropyl chloride/iso-pentane (85/15 parts by weight) as blowing agentat 1° C. is mixed into the resin. Once a uniform emulsion has formed,the resin mixture is cooled to between 5° C. and 10° C. Next, 40 g ofliquid para-toluene sulphonic acid/xylene sulphonic acid blend (65/35parts by weight) at 92% concentration, at 8° C. is quickly mixed in.Foaming commences immediately. Mixing of the acid into resin takes lessthan 10 seconds and 200 g of the resin mix is quickly poured into a30×30×5.0 cm picture frame mould preheated to 70-75° C.

A pressure of 40 to 50 kPa is applied to the lid of the mould topressurise the rising foam. The foam is cured at 70-75° C. for 10minutes. The foam sample is then post-cured in an oven for 2 to 12 hoursat 70° C. The foam board produced had an apparent density ofapproximately 40.5 kg/m³.

Comparative Example 6 demonstrates that lack of urea results in a foamwith poorer cell structure which results in higher aged thermalconductivity values (see Table 1).

Comparative Example 7

An attempt was made to prepare a foam using lithium carbonate as afiller. Only a low quality foam sample could be made due to reaction ofthe filler with the acid catalyst. The poor foam structure obtained wasdifficult to characterise accurately but was found to have high thermalconductivity and show a high water uptake.

Comparative example 7 demonstrates that use of a filler with a very highsolubility parameter (Ksp>>1×10⁻⁸), produces a foam which shows higherwater uptake when evaluated by test method (9). The foam structureresults in higher thermal conductivity.

In Table 1, no facing materials such as aluminium foil were present onthe surfaces of the foam board sample during thermal ageing.

The pH value of Comparative Example 1 is well below 5.0. ComparativeExample 2 results in a water uptake higher than 1 kg/m².

The use of pure isopropyl chloride (Comparative Example 3) as a blowingagent and the use of a mixture of 50 w % isopropyl chloride and 50 w %iso-pentane (Comparative Example 4), results in an aged thermalconductivity value higher than 0.025 W/m.K.

Comparative Examples 5 and 6 show respectively, the aged thermalconductivity value of a sample without plasticiser and urea.

TABLE 1 Thermal Conductivity After Thermal 25 weeks at 70° C. + AverageClosed Conductivity 5 weeks at 23° C. Cell Oxygen Water Cell Density(W/m · K and 50% RH Diameter Voids Index uptake Friability Ratio (kg/m³)at 10° C.) (W/m · K at 10° C.) pH (μm) (%) (%) (kg/m²) (%) (%) Ex 1 40.00.01968 0.02055 6.1 95 0.8 33 0.65 38 94 Ex 2 40.3 0.01948 0.02045 5.988 0.9 32 0.61 35 93 Ex 3 40.6 0.01981 0.02072 6.0 92 0.7 32 0.68 39 93Ex 4 39.8 0.02021 0.02321 6.3 96 0.7 32 0.71 37 93 Ex. 5 40.4 0.020060.02115 5.9 80 0.8 33 0.75 33 94 C. Ex. 1 40.1 0.01958 0.02095 2.7 850.6 33 1.24 28 94 C. Ex. 2 40.5 0.02060 0.02658 5.9 98 0.8 31 1.02 36 91C. Ex. 3 40.5 0.02009 0.02528 6.0 145 0.9 32 0.81 45 91 C. Ex. 4 39.80.01878 0.02807 6.1 60 0.6 32 0.69 29 94 C. Ex. 5 40.7 0.02005 0.025376.3 95 0.8 33 0.76 37 93 C. Ex. 6 39.5 0.01980 0.02911 5.9 89 0.7 330.72 30 92

The foam sample where magnesium carbonate is used results in anacceptable pH value. The water uptake of the product with magnesiumcarbonate however is higher compared to the water uptake of the foamsample with calcium carbonate. The foam sample where lithium carbonateis used as a filler gave very poor foam quality with high water uptake.These inferior results could be caused by the higher solubility constantof the fillers which react with the acid catalyst and can adverselyaffect foam quality. For this reason, a filler with a solubilityparameter below 1×10⁻⁸ is preferred.

Compound Formula K_(SP) (at 25° C.) lithium carbonate Li₂CO₃ 2.5 * 10⁻⁴magnesium carbonate MgCO₃ 3.8 * 10⁻⁸ calcium carbonate (calcite) CaCO₃3.8 * 10⁻⁹ barium carbonate BaCO₃ 5.1 * 10⁻⁹

Ionic compounds normally dissociate into their constituent ions whenthey dissolve in water. For example calcium carbonate:

CaCO₃(s)

Ca²⁺(aq)+CO₃ ²⁻(aq)

The equilibrium expression is:

$K_{c} = \frac{\left\lbrack {{Ca}^{2 +}({aq})} \right\rbrack \left\lbrack {{CO}_{3}^{2 -}({aq})} \right\rbrack}{\left\{ {{CaCO}_{3}(s)} \right\}}$

Where Kc is called the equilibrium constant (or solubility constant, thesquare brackets mean molar concentration (M, or mol/L), and curlybrackets mean activity. Since the activity of a pure solid is equal toone, this expression reduces to the solubility product expression:

K_(sp)[Ca²⁺(aq)][CO₃ ²⁻(aq)]

This expression says that an aqueous solution in equilibrium with(saturated with) solid calcium carbonate has concentrations of these twoions such that their product equals Ksp; for calcium carbonateKsp=3.8*10⁻⁹ measured at 25° C.

The higher solubility of magnesium and lithium carbonate alsocontributes to additional pressure build-up during the foaming processwhich is undesirable.

The phenolic foam of the present invention comprises a blowing agentcontaining a blend of chlorinated aliphatic hydrocarbon containing 2 to5 carbon atoms and an aliphatic hydrocarbon. The amount of acid catalystthat is used is controlled, and an inorganic filler such as calciumcarbonate is added to increase pH. The higher pH value of the foamensures that metallic material in contact with the phenolic foam is atreduced risk of corrosion.

The phenolic foam retains favourable fire-performance characteristics,and has stable thermal insulation performance over extended time scale.

The phenolic foam is used industrially as thermal insulation forconstruction materials.

1-64. (canceled)
 65. A phenolic foam made by foaming and curing afoamable phenolic resin composition that comprises a phenolic resin, ablowing agent, an acid catalyst and an inorganic filler characterised inthat the blowing agent comprises a blend of a chlorinated aliphatichydrocarbon containing 2 to 5 carbon atoms and an aliphatic hydrocarboncontaining from 3 to 6 carbon atoms, the inorganic filler is a metalhydroxide, or a metal carbonate with a Ksp less than 10⁻⁸ and in thatthe phenolic foam has a pH of 5 or more.
 66. The phenolic foam asclaimed in claim 65 wherein the phenolic resin has a molar ratio ofphenol groups to aldehyde groups in the range 1:1 to 1:3.
 67. Thephenolic foam as claimed in claim 66 wherein the molar ratio of phenolgroups to aldehyde groups is from 1.5 to 2.3.
 68. The phenolic foam asclaimed in claim 65 wherein the phenolic resin has a weight averagemolecular weight of from 400 to 3,000.
 69. The phenolic foam as claimedin claim 68 wherein the phenolic resin has a weight average molecularweight of from 700 to 2,000.
 70. The phenolic foam as claimed in claim65 wherein the blowing agent comprises 1 to 20 parts by weight per 100parts by weight of phenolic resin.
 71. The phenolic foam as claimed inclaim 65 wherein the blowing agent comprises isopropyl chloride and atleast one hydrocarbon of butane, pentane, hexane, heptane and theirisomers.
 72. The phenolic foam as claimed in claim 65 wherein theblowing agent comprises 60% or more of isopropyl chloride.
 73. Thephenolic foam as claimed in claim 65 wherein the blowing agent comprises75% or more of isopropyl chloride.
 74. The phenolic foam as claimed inclaim 65 wherein the blowing agent comprises 5% or more of hydrocarbon.75. The phenolic foam as claimed in claim 65 wherein the blowing agentcomprises 40% or less of hydrocarbon.
 76. The phenolic foam as claimedin claim 73 wherein the hydrocarbon is iso-pentane and is present as 15%by weight of the blowing agent.
 77. The phenolic foam as claimed inclaim 65 wherein the blowing agent blend comprises isopropyl chlorideand iso-pentane in a weight ratio of from 60:40 to 95:05.
 78. Thephenolic foam as claimed in claims 65 wherein the blowing agent blendcomprises isopropyl chloride and iso-pentane in a weight ratio of from65:35 to 90:10.
 79. The phenolic foam as claimed in claim 65 wherein theblowing agent blend comprises isopropyl chloride and iso-pentane in aweight ratio of from 70:30 to 85:15.
 80. The phenolic foam as claimed inclaim 65 wherein the acid catalyst comprises 5 to 25 parts by weight per100 parts by weight of phenolic resin.
 81. The phenolic foam as claimedin claim 65 wherein the acid catalyst comprises at least one ofbenzenesulphonic acid, para-toluene sulphonic acid, xylene sulphonic,naphthalene sulphonic acid, ethylbenzene sulphonic acid and phenolsulphonic acid.
 82. The phenolic foam as claimed in claim 65 wherein theinorganic filler is present in an amount of from 1 to 20 parts by weightper 100 parts by weight of phenolic resin.
 83. The phenolic foam asclaimed in claim 65 wherein the filler comprises a metal carbonate suchas calcium carbonate, barium carbonate, zinc carbonate.
 84. The phenolicfoam as claimed in claim 65 wherein the filler comprises calciumcarbonate.
 85. The phenolic foam as claimed in claim 65 comprising aplasticiser for the phenolic resin, and wherein the plasticisercomprises 0.1 to 20 parts by weight per 100 parts by weight of phenolicresin, and wherein the plasticiser comprises approximately 5 parts byweight per 100 parts by weight of phenolic resin, and wherein theplasticiser comprises a polyester polyol that is the reaction product ofa polybasic carboxylic acid selected from a dibasic to a tetra basiccarboxylic acid with a polyhydric alcohol selected from a dihydric to apentahydric alcohol.
 86. The phenolic foam as claimed in claim 85wherein the polyester polyol has a number average molecular weight of250 to 350 and a weight average molecular weight of 400 to
 550. 87. Thephenolic foam as claimed in claim 86 wherein the polybasic carboxylicacid used to synthesise the polyester polyol comprises at least one ofphthalic acid, isophthalic acid, terephthalic acid,naphthalene-2,3-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid,napththalene-2,6-dicarboxylic acid, adipic acid, pimeric acid, subericacid, azelaic acid, sebacic acid, cyclohexane-1,2-dicarboxylic acid,cyclohexane-1,3-dicarboxylic acid, and cyclohexane-1,4-dicarboxylicacid.
 88. The phenolic foam as claimed in claim 87 wherein the polybasiccarboxylic acid used to synthesise the polyester polyol comprises one ormore of phthalic acid, isophthalic acid, or terephthalic acid.
 89. Thephenolic foam as claimed in claim 85 wherein the polyhydric alcohol usedto synthesise the polyester polyol comprises at least one of ethyleneglycol, diethylene glycol, propylene glycol, dipropylene glycol,1,4-butane diol, 1,5-pentane diol, 1,6-hexane diol, neopentyl glycol,1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, and1,4-cyclohexane dimethanol.
 90. The phenolic foam as claimed in claim 89wherein the polyhydric alcohol used to synthesise the polyester polyolcomprises one or more of diethylene glycol, propylene glycol,dipropylene glycol, 1,4-butane diol.
 91. The phenolic foam as claimed inclaim 65 comprising a surfactant for the phenolic resin, and wherein thesurfactant comprises 1 to 6 parts by weight per 100 parts by weight ofphenolic resin, and wherein the surfactant is a castor oil-ethyleneoxide adduct wherein more than 20 moles but less than 40 moles ofethylene oxide are added per 1 mole of castor oil.
 92. The phenolic foamas claimed in claim 65 comprising an organic modifier for co-reactingwith the phenolic resin, and wherein the modifier comprises 1 to 10parts by weight of a compound having an amino group per 100 parts byweight of phenolic resin.
 93. The phenolic foam as claimed in claim 92wherein at least one amino group containing compound is selected fromurea, dicyandiamide and melamine and wherein the modifier optionallycomprises approximately 5 parts by weight of urea.
 94. The phenolic foamas claimed in claim 65 having one or more of the properties selectedfrom:— a thermal conductivity of 0.025 W/m.K or less (measured afterheat ageing for 175+/−5 days at 70+/−2° C.); the density of the phenolicfoam is from 10 to 100 kg/m³; the density of the phenolic foam is from10 to 45 kg/m³; having a closed cell content of 90% or more; having aclosed cell content of 92.5% or more; having a limiting oxygen index of30% or more; having a water uptake of less than 0.9 kg/m2; and having awater uptake of less than 0.8 kg/m2.
 95. The phenolic foam as claimed inclaim 65 having a facing on at least one surface thereof.
 96. Thephenolic foam as claimed in claim 95 wherein the facing comprises atleast one of glass fibre-non woven fabric, spun bonded-non woven fabric,aluminium foil, bonded-non woven fabric, metal sheet, metal foil, plywood, calcium silicate-board, plaster board, Kraft or other paperproduct, and wooden board.